1. Field of the Invention
The present invention is used for a pneumatic transporting apparatus for transporting powdered or granular materials, various kinds of raw materials for plastic, medicine, processed foods and the like, from a source from which the materials are supplied, through a transport pipe to a destination, utilizing pneumatic force of transporting gas, such as air, argon, nitrogen gas and the like, which is sucked in or pressurized to be fed, and, more specifically, relates to a method for transporting the powdered or granular materials by the pneumatic force with the transport pipe of smaller diameter used in such a manner that powdered or granular materials do not lodge (are not fixed) in the transport pipe and its apparatus.
2. Prior Art
In this kind of apparatus for transporting the powdered or granular materials by the pneumatic force, it is preferable that the powdered or granular materials, an article to be carried, such as a plastic pellet and the like, can be transported from an original transporting place to a transporting destination such that the powdered or granular materials do not lodge in the transport pipe. In order to attain this requirement, conventionally, various kinds of improvements in each of parts including the original transporting place, the transport pipe, and the transporting destination have been proposed. For example, trial ideas are that the original transporting place has a lower part of a storage vessel equipped with a feeder such as a rotary feeder and the like, compressed air is fed into a multiplicity of small holes being longitudinally made in a air pipe, smaller in diameter by fraction of the transport pipe, which is inserted into the transport pipe, and a cyclone separator is provided on the transporting destination.
Generally, the technical common sense in the industrial circle concerned is that a bore of the transport pipe ought to be adequate enough to prevent an apprehension of clogging the inside of the transport pipe with the powdered or granular materials, the article to be carried, such as a synthetic-resin-made pellet, i.e. it should be over 7 times as long as maximum length of particle of the powdered or granular materials.
As the transport pipe for transporting the ordinary synthetic-resin-made pellet by pneumatic force, conventionally, the transport pipe of larger diameter whose bore is approximately over 25 mm has been used. The fact is that even in the cases of grain whose maximum length of the particle of the powdered or granular materials is smaller than the afore-mentioned length and powder which is smaller than grain, the transport pipe of larger diameter whose bore is approximately over 25 mm is used.
In order to prevent the clogging of the transport pipe with the powdered or granular materials, as mentioned above, the bore of the transport pipe becomes unavoidably larger, as the industrial circle concerned recognized that the transport pipe of smaller diameter is not suitable for a practical application, because clogging of the transport pipe with the powdered or granular materials takes place.
In light of the recent preference for the small lot of plural productions, since a transportation of the powdered or granular materials with the transport pipe of larger diameter is led to an over-enlargement of the bore (sectional area) of the transport pipe in comparison with quantity of the powdered or granular materials to be transported, in addition to a larger space for piping, the piping work becomes complicated so that in terms of the facilities as well as the costs, an uneconomical situation is incurred.
In contrast with that, the transport pipe of smaller diameter overcomes the many shortcomings possessed by the afore-mentioned larger diameter. In this connection, the present inventors, as a result of their repeated research and experiments aimed at a realization of the transportation of the powdered or granular materials through use of the transport pipe of smaller diameter, discovered that even if the bore of the transport pipe, made of the synthetic resin or metal, is 2-6 times as long as maximum length of the particle of the powdered and granular materials, it is possible to transport the powdered and granular materials in such a manner that they do not lodge in the transport pipe. Nevertheless, the following questions are finally left unsolved : Namely, since a sectional area of flowing the powdered or granular materials is markedly narrowed at an inlet of the transport pipe, i.e. in vicinity of an outlet of the storage vessel containing the powdered or granular materials, the original transporting place is clogged with the powdered or granular materials. Further are that the outlet of the transport pipe, i.e. the transporting destination wherein the powdered or granular materials are collected such that they are separated from transporting gas, is also clogged with materials such that a separation efficiency between the transporting gas or dust and the powdered or granular materials is lowered.
As a result of the repeated study and development, by the present inventors, aimed at providing a solution of such subjects, as mentioned in the description hereinbelow, they succeed in developing means of solving the subjects.
In order to transport the powdered or granular materials by the pneumatic force with the afore-mentioned transport pipe of smaller diameter used, if appliances which have been conventionally used at the original transporting place and the transporting destination adopted, they become clogged with the powdered or granular materials, and the appliances are costly, being voluminous so that, after all, the aforementioned arrangement, which is different from the present inventor's pursuable product, cannot avoid an occurrence of clogging with the powdered or granular materials, miniaturize and simplify its construction, and provide the same at low costs.
Namely, as for the original transporting place, as mentioned above, the known idea is that the rotary feeder is provided on the lower part of the storage vessel. The rotary feeder employs a type in which a rotor having several units of blades around its rotational shaft is rotated in a case, and the powdered or granular materials being received among the blades after falling from the storage vessel located at the upper position are quantitatively discharged from an exhaust port located at the lower position. Since such a rotary feeder is required to perform such counter-actions as a transfer of the powdered or granular materials and blocking of the transporting gas at the same time, a critically problematic point lies in a gap between the rotor and the casing. From that view, the afore-mentioned rotary feeder has a structural defect that if the gap becomes smaller, although the air-tightness is improved, an increase in wear of the powdered or granular materials, caused by their engagement with the narrow gap, and a rotational resistance against the motion of the rotor is unavoidable. For this reason, also in the case of connecting this kind of rotary feeder to the transport pipe of smaller diameter, the same defect takes place.
As for the transporting destination, as mentioned above, a trial idea is that the cyclone separator is provided on an exhaust end of the transport pipe. In that case, the defect of cyclone separator which causes free vortex to give centrifugal force to the particle in air current, thereby collecting the powdered or granular materials from the gas in a separated manner, is that the size of particle which can be collected is over several .mu.ms and that such a separator is voluminous.